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RNA Interference

Why does control of gene expression usually occur at the transcription stage rather than the translation stage? Protein synthesis is a two stage process. DNA is used to produce mRNA (transcription) and then mRNA is used to produce proteins (translation). Transcription factors are a wide variety of molecules that control the production of mRNA. Factors that control the rate of translation are less well known – one is described in this animation. Unlike DNA, messenger RNA is a relatively short-lived molecule. If it is not used then it will probably break down shortly. Controlling the production of mRNA rather than its use, once produced, is probably a more efficient use of cellular resources.

View the animation below, then complete the quiz to test your knowledge of the concept.






1RNA intereference is a mechanism for silencing gene expression at the
A)level of replication.
B)level of transcription.
C)post-transcriptional but pre-translational level.
D)level of translation.
E)post-translational level.



2The protein ________ acts as an endonuclease in the first step of RNA interference.
A)interferon
B)phaser
C)sizer
D)dicer
E)vader



3RNA interference is stimulated in the presence of ________ in the cell.
A)single-stranded RNA
B)double-stranded RNA
C)single-stranded DNA
D)double-stranded DNA
E)proteins



4RISC is an RNA-protein complex that binds to cellular mRNAs.
A)True
B)False



5Antisense mRNA can be produced during the life cycle of all viruses.
A)True
B)False







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